Several Points Should Be Considered in the Selection of Filter Paper
Filter paper on the market can generally be divided into qualitative and quantitative. In the application of analytical chemistry, when inorganic compounds are separated by filtration to precipitate, the residue collected on the filter paper can be used to calculate the loss rate during the experiment. Qualitative filter paper produces more cotton fibers after filtration, which is an ideal choice for qualitative analysis; quantitative filter paper, especially ash-free filter paper, undergoes special processing procedures and can effectively resist chemical reactions, so the resulting impurities Less, can be used for quantitative analysis.
In addition to filter papers used in general laboratories, there are many applications of filter papers in daily life and engineering. Coffee filter paper is one of the widely used filter papers. The filter paper on the outer layer of tea bags provides high softness and high wet strength. Other air filter papers for testing suspended particles in the air, and fiber filter papers for different industrial applications.
The technical indicators of filter paper can be divided into two aspects, one is the filter characteristics of the filter paper, and the other is the physical characteristics. Filtration characteristics include air permeability, air resistance, maximum pore size, and average pore size. Physical properties include basis weight, thickness, stiffness, corrugation depth, burst resistance, resin content, etc.
Quantity: refers to the mass of filter paper per square meter, unit: g / m?
Thickness: refers to the thickness of the filter paper, excluding the corrugated depth. Unit: mm.
Air resistance: the resistance of filter paper to airflow. It is represented by the pressure drop value obtained by passing 100 liters of filter paper through 85 liters of air in one minute. The unit is mbar. Or the water column height (mm).
Corrugation depth: the depth of the groove pressed to strengthen the longitudinal stiffness of the filter paper, the unit is mm. In general, the value is 0.2mm.
Air permeability: the amount of air passing through the filter paper per unit time under a certain area and certain pressure (20 mm water column). The unit is L / m2 · s.
Nominal filtration accuracy: refers to the retention capacity of the filter paper to particles of a certain size, and the particle size of the tiny spheres when 50% can be retained or filtered out Unit: μm.
Maximum pore size: the void size calculated by the pressure when the first bubble emerges from the filter paper sample during the test. Unit: μm.
Average pore diameter: The pore diameter calculated by pressure when “dense” bubbling is called the average pore diameter. The unit is: μm.
Resin content: The percentage of resin in the weight of filter paper. Generally 10% ~ 30%.
Stiffness: the deformation resistance of filter paper. Unit: mg.
Burst: the maximum pressure that the filter paper can withstand per unit area. Unit: kPa.
1. The effective area is large, that is, the use area of the filter paper is large, the dust holding capacity is large, the resistance is small, the service life is long, and of course, the cost increases accordingly.
2. The finer the fiber diameter, the better the interception effect, and the correspondingly higher filtration efficiency.
3. The content of the binder in the filter material is high, the tensile strength of the paper is high, the filtration efficiency is high, the lint phenomenon is less, the dust background of the filter material is small, the resistance is good, but the resistance increases